Along an assembly line, diapers and various types of other disposable absorbent articles may be assembled by adding components to and otherwise modifying advancing, continuous webs of material. Webs of material and component parts used to manufacture diapers may include: backsheets, topsheets, absorbent cores, front and/or back ears, fastener components, and various types of elastic webs and components such as leg elastics, barrier leg cuff elastics, and waist elastics.
For quality control purposes, absorbent article converting lines may utilize various types of sensor technology to detect various types of defects in the webs and discrete components added to the webs along the converting line as absorbent articles are constructed. Example sensor technology may include vision systems, photoelectric sensors, proximity sensors, laser or sonic distance detectors, and the like. Sensor data may be communicated to an analyzer in various ways. In turn, the analyzer may be programmed to receive sensor data and reject or cull defective diapers after the final knife cut at the end of the converting line.
In some assembly operations, graphics are printed on individual components and/or continuous webs of material used to assemble the absorbent articles. The graphics may be provided by printing ink on substrate materials by various printing methods, such as flexographic printing, rotogravure printing, screen-printing, inkjet printing, and the like. In some configurations, the printing operations are performed separate to the assembly process, such as for example, printing the substrates offline wherein the printed substrates may be stored until needed for production. For example, printing operations may be accomplished on discrete printing lines, separately from converting lines that are dedicated to manufacturing disposable absorbent articles. After printing on the printing lines, the printed substrates are delivered to the converting lines, such as in a form of continuous webs comprising printed images thereon. In some configurations, the graphic printing may be done online during the article assembly process.
However, utilizing printed substrates in converting operations may create additional challenges when attempting to maintain aesthetically pleasing final assemblies. For example, various printing operations, alone or in combination with other article assembly operations, may result in graphics having various inconsistencies with respect to the desired quality of such graphics. It is to be appreciated that various factors may determine a level of the print quality.
In some print quality inspection regiments, the print quality of printed graphics may be judged solely by human beings. In turn, such an inspection regiment is completely subjective and may result in graphics having widely variable levels of quality being included in final article assemblies. In addition, it can be very cumbersome for human beings to inspect every printed graphic, and as such, inspection regiments may rely on random spot checks to inspect relatively low quantities of printed graphics utilized in final article assemblies. As technology has advanced and in order to help mitigate the negative impacts of human subjectivity involved with evaluating print quality, some inspection systems may utilize various automated inspection devices, such as for example, cameras, densitometers, and spectrophotometers. However, it is to be appreciated that not all defects may have equal impact on consumer acceptance with respect to the print quality of graphics included in various articles. For example, a print defect located on a front side of a diaper may have a relatively large impact on consumer acceptance when compared with the same print defect located in crotch region of the diaper. In another example, a print defect located on a front side of a container, such as a bag or box, may have a relatively large impact on consumer acceptance when compared with the same print defect located on a bottom side of the container. Therefore, although inspection systems may utilize automated inspection devices, human beings are still relied upon to conduct comparisons of printed samples to target samples as part of the overall print quality evaluation.
Consequently, there remains a need to configure print quality inspection systems that no longer rely on human subjectivity, but rather, perform objective evaluations of print quality and wherein such systems be configured to evaluate all or substantially all printed graphics on substrates intended for use in final article assemblies.